Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to an improved twin-
type slewing crane.
Twin-type slewing cranes are used for handling loads
on board ship. The individual cranes together make up the
twin crane being either used singly to load and unload indi-
vidual holds, or in combination for moving heavy freight.
Ordinary twin slewing cranes have a large mass
(weight) and are expensive as well, since each single crane
is constructed and arranged in such a way as to allow an
individual slewing motion. Each crane is thus rotatably
arranged on a common platform which itself can be rotated
around a foundation firmly anchored in the hull of the ship.
Such cranes have three slewing rims, three gear rings, three
slewing mechanisms and, in addition, a large common platform.
This type of construction makes for complex and expensive
assembly procedures and leads to high costs of transport,
assembly, inspection and maintenance.
Another type of twin slewing crane using only a single
gear ring and a slewing rim is known. These rim, or bearing,
however, are constructed so as to provide a double pivoting
link, that is, two bearing functions are combined so that the
middle race of the bearing is attached both to the foundation
of the crane and to the gear ring, while the outer race of the
bearing is connected by a collar arm to one crane, and the inner
race is connected, by another collar arm, to the other crane.
This type of bearing is very special, and since it produces a
slewing rim of very large diameter it is extremely expensive
and difficult to repair or replace if it is damaged. In addi-
tion to this, the positions o~ the collar arms in relation to
the bearing require different mechanical constructions in each
crane while at the same time the slewing mechanisms in each
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crane must be mounted differently. In one, the driving motor
is mounted upwards, and in the other it is mounted downwards.
Disadvantages are complications of construction and assembly
of the mechanism, and the fact that the driving motors must
be differently designed to allow drainage of condensing water.
The invention concerns a duplex slewing crane where
both cranes are located at the same distance from a common
vertical axis, where both are provided with a luffing jib
and, in relation to one another, are able to function within
a large angle of rotation, and where, whenever necessary,
both cranes are able to work together and thus are adjustable
to any given angle of rotation.
A feature of the present invention is to solve the
problem of combining two mechanically identical cranes whose
luffing jibs have the same maximum and minimum out-reach, two
slewing machineries and one slewing rim, and to simplify the
construction of a supporting bearing, safe to rotate and tip,
so that the assembly becomes simple and as cheap as possible
while the desired functions are achieved in operation of both
cranes.
According to a broad aspect of the present inven-
tion, there is provided a twin-type slewing crane comprising
an upright foundation with a ring gear secured thereon and
having a generally vertical axis. A generally horizontal base
plate is mounted on the foundation. Two individual cranes,
each having a luffing jib with means including a hoisting rope
running from a winch of that crane to a jib thereof for
raising and lowering the jib, are also provided. A supporting
means is provided for each crane, each mounting a respective
crane for rotation about the central axis at the same distance
from the central axis as one another. A rotating mechanism is
provided for each crane and projects therefrom into meshing
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relationship with the ring gear, whereby operation of the
rotating mechanism of at least one of the cranes propels at
least that respective crane about the said central axis. A
central axle is coaxially disposed on the central axis and
extends upwards from the base plate. Also provided are two
axially intercalated sets of two axially spaced bearings.
Each bearing has an inner race mounted on the axle and one
set has an outer race of each bearing thereof mounted on the
supporting means of one of the cranes and the other set has
an outer race of each bearing thereof mounted on the supporting
means of the other of the cranes. An anti-tipping roller means
is provided between the supporting means of each of the cranes
and the base plate.
The following drawings illustrate a preferred embo-
diment of the invention showing the construction of a twin
slewing crane where:
FIGURE 1 is a side view, partly in section, of a
first version of a twin slewing crane as
per this invention:
FIGURE 2 is a plan view of Figure 1, the cranes
being illustrated singly or together:
FIGURES 3, 4 and 5 are side views,partly in section,
of second, third and fourth versions of a
duplex slewing crane as per this invention:
and
FIGURE 6 shows, in highly simplified form, the under-
lying principles of a variant of the sup-
porting structures of the twin crane as
shown in Figures 1, 3, 4 and 5.
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In the first version of Figure 1, a foundation 1 having
a conical head 2, and provided with an end plate 3, is shown
mounted on the hull of a ship, not illustrated here, On this
end plate 3 is mounted an outer race 4 with a gear ring 5, to
a simple ball or roller-bearing connection, or so-called slewing
rim, generally designated 6. The inner race 7 of this slewing
rim 6, mounted on the outer race 4, is securely screwed to a
base plate 8. To this base plate 8 are attached a hollow
vertical bearing-mounted axle 9 and a primary supporting structure
10 with a vertical supporting plate 11 to which the first crane
12 is attached. The axle 9 runs through a vertical, circular
hole 13 in the supporting structure 10 to which it is here
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attached, This allows the axle 9 to rotate simultaneously with
the inner race 7 of the slewing rim 6 and the base plate 8.
Bolts, not illustrated here, are used to connect the supporting
plate 11 with a vertical back plate 14 on the crane 12. This
crane 12 is provided with a slewing machinery 15 which, by
means of a gear 16, extending downwards and rotating against
the gear ring 5, slews the crane 12 around the slewing axis o~
the base of the crane 12, here designated 17, In the version
illustrated here, the crane 12 is equipped with a luffing jib
18, luffing rope 19, luffing machinery20, hoisting wire 21 and
a hoisting machinery 22,
The primary supporting structure 10 is provided with
upper and lower horizontal recesses, 23 and 24, in which the
secondary supporting structure 27, also designated slewing
structure, provided with recess 28 and rotating round the
vertical bearing-mounted axle 9, is mounted on upper and lower
roller bearings 25 and 26. The slewing structure 27 is pro-
vided with a vertical plate 11' supporting the second crane
12'. Like the first crane 12, this supporting plate 11' is
bolted into a back plate 14' fastened to the back of the
second crane 12'. The slewing structure 27 of the second
crane 12' is thus mounted on the supporting structure 10 of the
first crane 12 by means of the vertical bearing-mounted axle 9.
Both supporting structures 10 and 27 are located at equal
heights and above the gear ring 5, and also each of the cranes
12 and 12'. The construction of the second crane 12' is
identical with that of the first crane, and through the action
of the slewing machinery 15' and its gear 16', which, like the
first crane 12 rotates against the gear ring ~, it can be made
to rotate relative to the first crane 12 and the vertical bearin~
mounted axle 9, and thereby around the slewing axis 17 of the
crane base as well.
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A connecting tube 29 runs through the vertical bearing-
mounted axle 9. The lower end of this tube is attached to a
bracket 30 fastened to the end plate 3, while the upper end is
mounted in the vertical bearing-mounted axle 9 by means of a
bearing 31. The tube 29 comprises a slip-ring device 32 for
the provision of electricity to the cranes 12 and 12'.
In order to displace the second crane 12' when nece-
ssary, one or more travelling wheels 33 are provided and moving
on a circular track attached to the base plate 8.
Figure 2 shows how each crane 12 and 12' can work
individually and how the second crane 12' can be manoeuvred in-
to a position - shown here in dotted lines - next to the first
crane 12 enabling both to wor~ together as a twin slewing crane.
The angle of rotation of the second crane 12' relative to the
first crane 12 is at least 180. If both cranes are slewed
simultaneously the angle of rotation is unlimited. If both are
working together, the cranes 12 and 12' being locked into
position beside one another (not illustrated here) and the
rotation is unlimited.
me supporting structure 10 and slewing structure 27
are built so that they form an angle in order to be able to
bring the cranes 12 and 12' into a position where they are
roughly parallel with each other andto achieve a suitable dis-
tance ~etween the load hooks. The angle ~ between the centre
line 35 of the first luffing jib 18 and the centre line 36 of
the supporting structure, and between the centre line 37 of the
second luffing jib 18' and the centre line 38 of the slewing
structure 27, is thus less than 90.
If both cranes are to be operated simu~taneously,the
luffing machinery 20 and 20' and the hoisting machinery 2~ and
22' must be synchronized so that the movement of the jibs and
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hoisting ropes are equal. The slewing machinery 15 and 15',
too, must be synchronized in order to allow the simultaneous
rotation of the cranes 12 and 12', unless one machinery is
powerful enough to be able to slew both cranes alone. This
twin slewing crane is thus capable of handling loads twice as
heavy as the maximum working load of a single crane.
Figure 3 shows another version of a twin slewing
crane, from which it is apparent that the bearing-mounted axle
9 attached to the base plate 8, illustrated in Figure 1, has
been replaced by a hollow, vertical, articulated axle 39
attached to the primary supporting structure 10 but not to the
base plate 40. In this version, the function of the articulated
axle 39 is simply to serve as a hinged axle on which the second
crane 12' is suspended by means of bearings 25 and 26, and
around which the second crane 12' can be made to rotate
relative to the first crane 12.
The version to be used is determined by the mechanical
dimensions of the crane with regard to operational loads and
stress.
Figure 4 shows a third version of a twin slewing
crane, from which it is apparent that the articulated axle 39,
illustrated in Figure 3, has been replaced by upper and lower
tubular stubs, 41 and 42. These are attached to the supporting
structure 10 but not to the base plate 40. The tubular stubs
function as pivot pins on which the second crane 12' is
suspended by means of bearings 25 and 26 and around which the
second crane 12' can be made to rotate relative to the first
crane 12.
Figure 5 shows a fourth version of a twin slewing
crane, from which it is apparent that, unlike Figures 1, 3 and
4, there is no slewing rim, that both cranes 12 and 12' are
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suspended on a hollow, non-rotating vertical column axle 43
and that the base plate, here designated 44, is fixed to the
foundation 45 of the crane.
The foundation 45 of the crane has a conical head 46,
a twin supporting plate 47 and the base plate 44 just mentioned.
These two plates are rigidly mounted and cannot rotate. A gear
ring 48 is mounted on the foundation of the crane 45, into which
the gears, 16 and 16', of the slewing machinery 15 and 15', of
the individual cranes 12 and 12' mesh. The upper end of the
vertical column axle 43 is covered by a plate 49 supporting a
slip-ring device 32 and is fitted with a bearing flange 50,
located at some distance away from the lower end of the axle,
and a supporting flange 51 with a stub axle 52 at its lower end.
Stability of the vertical column axle 43 is achieved by fixing
the supporting flange 51 and stub axle 52 firmly to the support-
ing plate, while the bearing flange 50 is attached to the base
plate 44. The primary supporting structure 55, mounted on the
axle 43 by means of upper and lower roller bearings 53 and 54,
carries a vertical supporting plate 56 to which the first
~rane 12 is attached. This supporting plate 56 is fastened by
bolts (not illustrated here) to a vertical plate 14 on the back
of the crane 12. The primary supporting structure 55 is pro-
vided with upper and lower horizontal recesses, 57 and 58, in
which the secondary supporting structure 61, which rotates
around the vertical column axle 43, is mounted on upper and
lower roller bearings 59 and 60. The secondary supporting
structure 61 is provided with upper and lower horizontal recesses
62 and 63 respectively, into which the roller bearings 53 and
54 mentioned above, running around the vertical column axle ~3
~0 are fitted. The secondary supporting structure 61 has a verti-
cal plate 56 which carries the second crane 12' and which, like
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the first crane 12, is fastene~ by bolts to a plate 14' attache~
to the back of the second crane 12'. The construction is other-
wise the same as sho~ in Figures 1, 3 and 4. The cranes 12
and 12', working both singly and together, move in the same way
as those shown in the first version.
In order to offset the downward pull of the first
and second cranes 12 and 12', each is provided, if their size
should make it necessary, with one or more travelling wheels,
33 and 33', moving on a circular track 64 attached to the base
plate 44.
The version shown in Figure 5 has the advantage that
instead of the large slewing rim with two smaller roller bearings
as used in the first, second and third versions illustrated in
Figures 1, 3 and 4, four small roller bearings can be used
which do away with the difficulty of obtaining an expensive
slewing rim manufactured in small series only, and which allow
roller bearings to be used which can be manufactured in large
series and are ~ence cheaper and more standardized.
Figure 6 shows, in highly simplified form, the funda-
mental principle of a variant of the supporting structures ofth~ cranes 12 and 12'. The structures, here designated 65 and
66, are provided with vertical supporting plates 67 and 67'
which at their lower end have horizontal projections, 68 and
68'. 8y this arrangement, the vertical plates 14 and 14' on
the back of the cranes 12 and 12' can be bolted to the support-
ing plates 67 and 67' while the bottom of the cranes can be
bolted to the projections 68 and 68', thus increasing the
strength of the attachment of the cranes to their supporting
structures 65 and 66. In certain smaller versions of this
crane type, bolting the cranes to the projections only wou1d
be sufficient.
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Some of the advantages offered by twin slewing cranes
of the type described herein may be summarized as follows:
By using a vertical bearing axle, an articulated axle or
tubular axle stubs co~bined with the structures supporting each
crane, and by attaching the crane to a base plate which can
be rotated on a slewing rim in versions 1, 2 and 3 a single
slewing rim and two mechanically identical cranes without
individual slewing rim or gear rings can be used.
By using a simple vertical column axle, in version 4, a
number of roller bearings and supporting structures to carry
the individual cranes, even the single slewing rim mentioned
above can be avoided. Here, too, mechanically identical cranes
without individual slewing rims can be used.
By eliminating the platform used in conventional cranes
the height of this type of twin crane can be decreased.
By eliminating the large size slewing rims and gear
rings hitherto used in the construction of the base of single
cranes, and by omitting in the platform, the construction is
simplified at the same time as building costs and total weight
are reduced.
By eliminating all large size slewing rims in the fourth
version and instead using more conventional roller bearings,
the difficulties associated with obtaining and purchasing
expensive special bearings is avoided.
By the method of construction of this twin crane, and by
using the slewing machineries of the individual cranes for
operation of the cranes either singly or as a pair, the slewing
machinery and provision for power supply hitherto used can be
avoided, meaning that testing, inspection and maintenance can
be more simply carried out.
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By the method of construction used, costs of transport
and assembly on board ship can be reduced as compared with
conventional cranes.
Details of design of the examples of the embodiment
described herein may be modified within the limits of the
claims. Thus, in versions 1, 2 and 3, a recess may be provided
in the middle of the supporting structure instead of at its
upper and lower ends, and a bearing may be mounted there in-
stead. Again, the number of bearings could, e.g. be increased
or that the roller bearings replaced by slide bearings, or the
supporting structures and slewing structures may be provided
with a number of recesses following the principle of the
"piano hinge". Another possible modification would be to
place the travelling wheels at a greater distance fram the
common vertical axis of the crane, under each individual crane,
for instance.
This application is a division of Canadian Patent
Application Serial ~o. 287,443 filed September 26, 1977.
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